Global System For Mobile Communication Signal Research Articles

A modified cost-231-hata path loss model for typical semi-urban environments in Nigeria

Outdoor path loss propagation modeling is critical in the planning and design of the coverage area by the Global System for Mobile Communication (GSM). For the best prediction of GSM signal at any location within its coverage region, an accurate forecast based on critical characteristics and a mathematical model is necessary. Multiple studies on path loss propagation model prediction for GSM networks conducted at various semi-urban environments in Nigeria proclaimed that propagation path loss models may provide different results when utilized in environments other than those in which they were initially designed, that car drive-test methodology was used during the data collection, and that COST-231-Hata model provides closet prediction to the practical measure values. This paper created an appropriate path loss model based on the COST-23-Hata model and outdoor measurement at 1800 MHz frequency range for the semi-urban area of Kwara State, Nigeria. The created model was used and validated with the measured data and COST-231-Hata model at other different semi-urban environments in Nigeria. The results analysis shows that the created model performed satisfactorily given the closet path loss prediction to the practical measure path loss values at all the study locations. It also gives the lowest Square Root Means Error (SRME) and Standard Deviation (SD) in all the base stations that were tested in semi-urban environments. The newly created model would therefore be more appropriate for GSM 1800 network design and installation in semi-urban environments in Kwara State, Nigeria, as well as any other semi-urban locations in Nigeria.

EFFECT OF THICK VEGETATION COVER, BUILDING OBSTRUCTIONS, AND EARTH TERRAIN ON THE QUALITY AND PERFORMANCE OF THE GSM SIGNAL AT THE FEDERAL POLYTECHNIC ADO-EKITI

Wireless communication system performance is fundamentally constrained by the mobile radio channels such as the Global System for Mobile Communication (GSM). The transmission path between the base transceiver station and the mobile station can range from line-of-sight to substantially obstructed environmental situations such as buildings, earth undulation valleys, and thick vegetation being the primary cause of poor network performance in and around the school perimeter. Mobile radio channels are incredibly unpredictable and do not provide simple analysis, in contrast to stationary and reliable wired channels. This research work, therefore, investigates the effect of thick vegetation cover, building obstructions, and earth terrain on the quality and performance of the GSM signal at the Federal Polytechnic Ado-Ekiti environs. A model for path loss (attenuation) is developed according to the Longley-Rice propagation model that forecasts the long-term median transmission loss over uneven terrain in comparison to the free-space transmission loss. The model was created for frequencies in the 20 MHz to 40 GHz range and path lengths in the 1 to 2,000 km range. The analysis of the results obtained shows that the path loss (attenuation) produced due to the effect of vegetation, building obstructions, and the earth undulation structures are quite significant. The solution of cell creation as a primary way of improving the quality of the GSM signal reception in the school perimeter without necessarily destroying the natural environment or demolishing any existing building is proposed.

AJ-Olu-1: An Innovative Path Loss Model for Typical Nigerian Urban Environments

The modeling of outdoor path loss propagation is critical in the planning and construction of the Global System for Mobile Communication (GSM) coverage area. For GSM signal prediction at any location inside its service region, a precise forecast based on critical characteristics and a mathematical model is required. Numerous research findings on path loss propagation model forecast for GSM mobile networks conducted in various cities in Nigeria revealed that the COST231-Hata model gives closer prediction to most of the practical measure path loss values. Based on the existing COST-23-Hata path loss model and outdoor measurements at 1800 MHz frequency range within Ilorin metropolis, this paper proposed a suitable path loss model. The developed model was used and validated in various locations throughout Ilorin city with the measured and COST-231 Hata models. The analysis of the results revealed that the developed model performed satisfactorily in terms of the closest path loss prediction to the practical measure path loss values at all study locations. It also has the lowest Square Root Means Error and Standard Deviation (SD) of any Base Station (BTS) tested in Ilorin, Nigeria. As a result, it is concluded that the newly developed AJ-Olu-1 model is more suitable for GSM 1800 network design and installation in Ilorin City, Nigeria, as well as other cities in Nigeria and other cities outside Nigeria with similar environments.

Effectively Optimized Dual-band Frequency Selective Surface Design for GSM Shielding Applications

Nowadays, global system for mobile communication (GSM) systems are widely used. Therefore, the impact of mobile GSM signals on human health is one of the current research topics. Furthermore, electromagnetic interference caused by GSM signals can be a significant threat to electronic devices today. To overcome these problems, the surfaces of electronic equipment and exterior or interior walls of buildings can be covered with frequency selective surface (FSS) that stops unwanted GSM signals and passing the other signal. This work presents a novel dual-band FSS that attenuates the 900 MHz and 1800–2170 MHz GSM bands by at least 10 dB in the transmission direction. At the design stage, nested geometries are used to achieve multi-stop band frequency response. The proposed design is effectively optimized by utilizing the equivalent circuit geometries and current and electric field distribution diagrams. So, minimum of 10 dB attenuation is achieved in targeted GSM bands for all polarizations and up to 60 degrees (except TM 60 degrees) of incidence angles.

Heart rate variability in healthy young adults exposed to global system for mobile communication (GSM) 900-MHz radiofrequency signal from mobile phones

Given the large number of mobile phone users and the increasing exposure to radiofrequency electromagnetic field (RF-EMF) worldwide, we aimed to study the effect of RF-EMF related to mobile phones on heart rate variability (HRV). Twenty-six healthy young adults participated in two experimental sessions with a double-blind, randomized and counter-balanced crossover design. During each session, participants were exposed for 26 min to a sham or real 900 MHz RF-EMF, generated by a commercial dual-band Global System for Mobile technology (GSM) mobile phone. We recorded an electrocardiogram at rest during the exposure. We evaluated HRV by time- and frequency-domain analysis. Evaluation of time-domain HRV parameters revealed a statistically significant increase of the standard deviation of interbeat intervals (SDNN) during the real exposure. Other time-domain parameters were not affected. Analysis in the frequency-domain demonstrated that total spectral power and low-frequency band (LF) absolute power were significantly increased during exposure (p = .046 and p = .043, respectively). However, other parameters were not affected. In conclusion, it seems that most HRV parameters were not affected by GSM signal exposure in our study. The weak effect observed on HRV frequency-domain is likely to represent a random occurrence rather than a real effect.

Development of Frequency GSM Signal Jammer

This paper gives an explanation to the concept of mobile Jamming and explores jamming in the two popular mobile networks: Global system for mobile communication (GSM) and digital cellular network (DCS). The designed intelligent jamming system blocks the controller channel only, also it operates only if an active mobile is in the controlled area. The ADS - advance Design System for Agilent software package is used analyzed and simulated the mobile jamming system. The Mobile Detector Phone Jammer successfully jammed all the four operators but the radius of the range did not get as expected in the designed, this project only focuses on blocking the signal transmission between the ranges 935 to 960 MHz when tested and performed well. This can be effectively find its use in School Examination hall and religion worship centers. Keywords—Jammer, Mobile Phone, Network, Signal, Frequency

Selection and Optimization of Most Suitable Path Loss Prediction Model for Suburban City in Nigeria Using Spline Interpolation

Path loss is an attenuation of Global System for Mobile Communication (GSM) signal between Base Transceiver Station (BTS) and Mobile Station (MS). Path loss helps network engineers in planning, designing and implementing telecommunication networks. This work examines the applicability of Hata, COST 231, ECC – 33, Ericsson and SUI models in a medium city (Mubi) in Adamawa State, Nigeria. Root mean square error (RMSE) between the measured and the predicted losses (output of the models) is obtained as 7.632dB, 14.736dB, 10.593dB, 0.639dB and 23.491dB respectively. Ericsson model is found to have the least RMSE. Therefore, it is selected as the best fit model and modified. Furthermore, the modified model is optimized to recover missing or to eliminate unwanted information in the radio path using spline interpolation. The optimized model can be employed for the deployment of network resources in suburban areas of Nigeria, especially in Mubi town in Adamawa State, in order to significantly enhance GSM signal QoS. It is recommended that fuzzy logic and spline interpolation techniques may be integrated and employed to further minimize the error obtained in this work.

An experimental study of indoor RSS-based RF fingerprinting localization using GSM and Wi-Fi signals

Localization of mobile users in indoor environments has many practical applications in daily life. In this paper, we study the performance of the received signal strength (RSS)-based radio frequency (RF) fingerprinting localization method in a shopping mall environment considering both calibration and practical measurement cases. In the calibration case, the test data for the RSS fingerprinting database are built offline by receiving signals from Global System for Mobile Communications (GSM) base stations, which are collected by a dedicated measurement tool, i.e. the Test Mobile System. In order to see the localization performance, the k-nearest neighbors (K-NN) and random decision forest (RDF) algorithms are implemented. The RDF algorithm provides a better localization performance than K-NN in this case. For the practical implementations, the RSS values of both GSM and Wi-Fi signals are collected by ordinary smartphones. Localization is performed using different classification algorithms, i.e. BayesNet, support vector machines, K-NN, RDF, and J48. Moreover, the effects of the received signal type, phone type, and number of reference points on localization performance are investigated.

The Impact of Weather Condition on Radio-Based Distance Estimation: A Case Study in GSM Networks With Mobile Measurements

Distance estimation based on the received signal strength (RSS) of wireless radio has been extensively studied; however, the estimation accuracy is susceptible to radio propagation conditions, particularly during periods of precipitation. This study performed experiments on the 1.8-GHz band of Global System for Mobile Communications (GSM) networks at Yuan Ze University, Taoyuan, Taiwan, sensing actual radio power signals using mobile phones and recording transmission conditions during various weather events. The aim was to compare RSS performance under dry and wet weather conditions and study the dynamics of distance estimation from theoretical and empirical perspectives. Traditional rain attenuation models have largely discounted the impact of precipitation on GSM signals due to the relatively low frequency band; however, on-site experimental results demonstrated that dynamic weather significantly degrades accuracy in distance estimation. This study employed a typical rain attenuation model and a radio propagation model to evaluate errors in distance estimation under various rain conditions, i.e., heavy rain, extremely heavy rain, torrential rain, and extremely torrential rain, in accordance with the standards set out by the Central Weather Bureau, Taiwan. This study also investigated the RSS attenuation under various wind speeds. The Cramer–Rao lower bound (CRLB) was used as a benchmark for comparison.

Determination of GSM Signal Penetration Loss in some Selected Buildings in Rivers State, Nigeria

The qualities of indoor signal reception are governed by the mechanism of reflection, refraction, diffraction and scattering of signal propagation through buildings which are dependent on the material of the building structure. These indoor outages can be traced to building penetration loss. Penetration loss depends on the type of building material used. This research work is a determination of signal penetration loss in some selected buildings in Rivers state, Nigeria. Global system for mobile communication (GSM) signals of MTN, GLOBACOM, AIRTELand ETISALAT networks were measured using Radio Frequency Signal Tracker in five different buildings (mud house with thatched roof, mud house/rusted corrugated iron sheet roof, sandcrete building/rusted corrugated iron sheet roof, sandcrete building/unrusted corrugated iron sheet roof and building with alucoboard wall cladding) in Port Harcourt metropolis in Nigeria. The results showed that buildings with alucoboard wall cladding has the highest GSM signal penetration loss while the sandcrete building/unrushed corrugated iron sheet roof has the lowest GSM penetration signal loss. http://dx.doi.org/10.4314/njt.v34i3.26

Effects of 900 MHz Radiofrequency Radiation on Skin Hydroxyproline Contents

The present study aimed to investigate the possible effect of pulse-modulated radiofrequency radiation (RFR) on rat skin hydroxyproline content, since skin is the first target of external electromagnetic fields. Skin hydroxyproline content was measured using liquid chromatography mass spectrometer method. Two months old male wistar rats were exposed to a 900 MHz pulse-modulated RFR at an average whole body specific absorption rate (SAR) of 1.35 W/kg for 20 min/day for 3 weeks. The radiofrequency (RF) signals were pulse modulated by rectangular pulses with a repetition frequency of 217 Hz and a duty cycle of 1:8 (pulse width 0.576 ms). A skin biopsy was taken at the upper part of the abdominal costa after the exposure. The data indicated that whole body exposure to a pulse-modulated RF radiation that is similar to that emitted by the global system for mobile communications (GSM) mobile phones caused a statistically significant increase in the skin hydroxyproline level (p = 0.049, Mann-Whitney U test). Under our experimental conditions, at a SAR less than the International Commission on Non-Ionizing Radiation Protection safety limit recommendation, there was evidence that GSM signals could alter hydroxyproline concentration in the rat skin.

Effects of the exposure to intermittent 1.8 GHz radio frequency electromagnetic fields on HSP70 expression and MAPK signaling pathways in PC12 cells

Purpose: We previously reported effects on heat shock protein 70 (HSP70) mRNA expression, a cytoprotective protein induced under stressful condition, in human trophoblast cells exposed to amplitude-modulated Global System for Mobile Communication (GSM) signals. In the present work the same experimental conditions were applied to the rat PC12 cells, in order to assess the stress responses mediated by HSP70 and by the Mitogen Activated Protein Kinases (MAPK) in neuronal-like cells, an interesting model to study possible effects of mobile phone frequencies exposure.Materials and methods: HSP70 gene expression level was evaluated by reverse transcriptase polymerase chain reaction, HSP70 protein expression and MAPK phosphorylation were assessed by Western blotting. PC12 cells were exposed for 4, 16 or 24 h to 1.8 GHz continuous wave signal (CW, carrier frequency without modulation) or to two different GSM modulation schemes, GSM-217Hz and GSM-Talk (which generates temporal changes between two different GSM signals, active during talking or listening phases, respectively, thus simulating a typical conversation). Specific adsorption rate (SAR) was 2 W/kg.Results: After PC12 cells exposure to the GSM-217Hz signal for 16 or 24 h, HSP70 transcription significantly increased, whereas no effect was observed in cells exposed to the CW or GSM-Talk signals. HSP70 protein expression and three different MAPK signaling pathways were not affected by the exposure to any of the three different 1.8 GHz signals.Conclusion: The positive effect on HSP70 mRNA expression, observed only in cells exposed to the GSM-217Hz signal, is a repeatable response previously reported in human trophoblast cells and now confirmed in PC12 cells. Further investigations towards a possible role of 1.8 GHz signal modulation are therefore advisable.

Effect of Environmental Parameters on GSM and GPS

This work proposes analysis effect of environmental parameters on Global System for Mobile Communication (GSM) and Global Positioning System (GPS). This paper presents variation in GSM signal strength with respect to weather parameters. There are many sources of deviation for both issues, but into this research our main focus on Tropospheric delays. The results show humidity, pressure, temperature and air condition effect signal strength values of GSM and accuracy of GPS. The minimum and maximum measurements were recorded for GSM in the range - 89 and - 41 dBm where -89 is low signal strength and -41 is high signal strength. The accuracy of GPS were calculated and compared at different points. Result of this research showed that the tropospheric delay produce 6 to 14 meters deviation on same landmark at different weather parameters value.

Induction of an adaptive response in human blood lymphocytes exposed to radiofrequency fields: Influence of the universal mobile telecommunication system (UMTS) signal and the specific absorption rate

The induction of an adaptive response (AR) was examined in human peripheral blood lymphocytes exposed to non-ionizing radiofrequency fields (RF). Cells from nine healthy human volunteers were stimulated for 24h with phytohaemagglutinin and then exposed for 20h to an adaptive dose (AD) of a 1950MHz RF UMTS (universal mobile telecommunication system) signal used for mobile communications, at different specific absorption rates (SAR) of 1.25, 0.6, 0.3, and 0.15W/kg. This was followed by treatment of the cells at 48h with a challenge dose (CD) of 100ng/ml mitomycin C (MMC). Lymphocytes were collected at the end of the 72h total culture period. The cytokinesis-block method was used to record the frequency of micronuclei (MN) as genotoxicity end-point. When lymphocytes from six donors were pre-exposed to RF at 0.3W/kg SAR and then treated with MMC, these cells showed a significant reduction in the frequency of MN, compared with the cells treated with MMC alone; this result is indicative of induction of AR. The results from our earlier study indicated that lymphocytes that were stimulated for 24h, exposed for 20h to a 900MHz RF GSM (global system for mobile communication) signal at 1.25W/kg SAR and then treated with 100ng/ml MMC, also exhibited AR. These overall data suggest that the induction of AR depends on RF frequency, type of the signal and SAR. Further characterization of RF-induced AR is in progress.

Measurements of the effects of multipath interference on timing accuracy in a cellular radio positioning system

The authors present a quasi-interferometric technique for measuring the flight times of signals broadcast by global system for mobile communication (GSM) transmitters, together with measurements made using the technique in and around Cambridge, UK. The data are used to determine the errors associated with GSM signal arrival times in various environments. The majority of the timing errors in all signal environments lie in the range -1 to +1.5 μs, with the tails of the distributions extending beyond +3 μs. The authors show that these large timing errors are caused by the distortions of the cross-correlation peaks used to determine the signal arrival times as a result of coherent multipath interference. Models of timing errors, based on Cauchian distributions, fit the experimental data better than those based on symmetrical or skewed Gaussian functions. This has implications for attempts to combine GSM and global navigation satellite system measurements using Kalman filters.

Electric and magnetic fields do not modify the biochemical properties of FRTL-5 cells

Electric and magnetic fields (EMF) might be involved in human disease and numerous research and scientific reviews have been conducted to address this question. In particular thyroid structural and functional alterations caused by various forms of non-ionizing radiation have been described. The aim of this study was to analyze the possible effects of EMF on thyroid, in particular we analyzed the effects caused by a GSM (Global System for Mobile Communications) signal (900 MHz) on cultured thyroid cells (FRTL- 5). The experimental setup was designed in order to expose samples to a radiofrequency wave in well-controlled conditions. We used the FRTL-5 cell line, an epithelial monoclonal continuous cell line derived from Fisher rat thyroid tissue growing as monolayer, expressing the TSH receptor and the sodium-iodide symporter (NIS). FRTL-5 were subsequently irradiate for 24, 48, and 96 h with EMF (800-900 MHz, power-frequency of mobile communication systems) and iodide uptake and cAMP production were measured. The irradiation of cells with EMF at 900 Mhz for 24, 48, and 96 h did not influence the level of cAMP production and was not able to modify iodide accumulation in FRTL- 5 cells with respect to basal conditions. In conclusion, EMF do not seem to be able to interfere with the biochemical properties of FRTL-5 cells in vitro.

GFAP expression in the rat brain following sub-chronic exposure to a 900 MHz electromagnetic field signal

Purpose: The rapid development and expansion of mobile communications contributes to the general debate on the effects of electromagnetic fields emitted by mobile phones on the nervous system. This study aims at measuring the glial fibrillary acidic protein (GFAP) expression in 48 rat brains to evaluate reactive astrocytosis, three and 10 days after long-term head-only sub-chronic exposure to a 900 MHz electromagnetic field (EMF) signal, in male rats.Methods: Sprague-Dawley rats were exposed for 45 min/day at a brain-averaged specific absorption rate (SAR) = 1.5 W/kg or 15 min/day at a SAR = 6 W/kg for five days per week during an eight-week period. GFAP expression was measured by the immunocytochemistry method in the following rat brain areas: Prefrontal cortex, cerebellar cortex, dentate gyrus of the hippocampus, lateral globus pallidus of the striatum, and the caudate putamen.Results: Compared to the sham-treated rats, those exposed to the sub-chronic GSM (Global System for mobile communications) signal at 1.5 or 6 W/kg showed an increase in GFAP levels in the different brain areas, three and ten days after treatment.Conclusion: Our results show that sub-chronic exposures to a 900 MHz EMF signal for two months could adversely affect rat brain (sign of a potential gliosis).

GSM 신호 측정기의 소프트웨어 구현

본 논문에서는 GSM (Global System for Mobile Communication) 단말의 성능을 측정하기 위한 측정기의 기능을 소프트웨어로 구현하고 GSM 신호 발생기를 통해 발생된 신호를 이용해 구현된 소프트웨어 측정기의 성능을 평가해본다. 일반적으로 통신신호 측정기는 매우 정밀한 정확도를 필요로 하므로 정확도가 충분히 높지 않은 일반 통신 모뎀 수준의 수신 알고리듬을 직접적으로 측정기에 적용할 수는 없다. 본 논문에서는 GSM 신호의 정밀한 측정을 위한 새로운 GSM 신호의 수신 알고리듬을 제안한다. 제안된 GSM 수신 알고리듬에는 2단계(개략적 단계, 미세 단계)의 파라미터(심볼 타이밍, 주파수 오프셋, 반송파 위상) 추정방식을 사용하였다. 또한 수신신호의 보간을 이용하여 수신 신호 샘플의 개수를 증가시킴으로서 측정의 정확도를 향상시켰다. 본 논문에서 제안된 GSM 신호 측정 방식은 하드웨어를 구현하기 전에 소프트웨어를 이용하여 사전에 측정 성능을 검증하는데 사용될 수 있다. 또한 구현된 소프트웨어 알고리듬을 속도측면에서 최적화함으로서 직접 GSM 신호 측정을 위한 상용 시스템으로도 이용할 수 있다. In this paper, we implement measurement functionality for performance measurement of the GSM (Global System for Mobile Communication) terminal by using software. Generally speaking, the receiving algorithms in normal modems cannot be used directly to the measurement system due to the lack of the algorithm accuracy. In this paper, we propose the new receiver algorithm for precise GSM signal measurements. In the receiving algorithm, 2-stage (coarse stage, fine stage) parameters estimation (symbol-timing, frequency offset, carrier phase) scheme is used. To improve the estimation accuracy, we increase the number of the received signal samples by interpolation. The proposed GSM signal measurement algorithm can be used for verifying the hardware measurement system. In addition, the proposed algorithm can be used for the commercial system through code execution speed optimization.

Short‐term exposure to mobile phone base station signals does not affect cognitive functioning or physiological measures in individuals who report sensitivity to electromagnetic fields and controls

Individuals who report sensitivity to electromagnetic fields often report cognitive impairments that they believe are due to exposure to mobile phone technology. Previous research in this area has revealed mixed results, however, with the majority of research only testing control individuals. Two studies using control and self-reported sensitive participants found inconsistent effects of mobile phone base stations on cognitive functioning. The aim of the present study was to clarify whether short-term (50 min) exposure at 10 mW/m(2) to typical Global System for Mobile Communication (GSM) and Universal Mobile Telecommunications System (UMTS) base station signals affects attention, memory, and physiological endpoints in sensitive and control participants. Data from 44 sensitive and 44 matched-control participants who performed the digit symbol substitution task (DSST), digit span task (DS), and a mental arithmetic task (MA), while being exposed to GSM, UMTS, and sham signals under double-blind conditions were analyzed. Overall, cognitive functioning was not affected by short-term exposure to either GSM or UMTS signals in the current study. Nor did exposure affect the physiological measurements of blood volume pulse (BVP), heart rate (HR), and skin conductance (SC) that were taken while participants performed the cognitive tasks.

Acute Mobile Phones Exposure Affects Frontal Cortex Hemodynamics as Evidenced by Functional Near-Infrared Spectroscopy

This study aimed to evaluate by functional near-infrared spectroscopy (fNIRS), the effects induced by an acute exposure (40 mins) to a GSM (Global System for Mobile Communications) signal emitted by a mobile phone (MP) on the oxygenation of the frontal cortex. Eleven healthy volunteers underwent two sessions (Real and Sham exposure) after a crossover, randomized, double-blind paradigm. The whole procedure lasted 60 mins: 10-mins baseline (Bsl), 40-mins (Exposure), and 10-mins recovery (Post-Exp). Together with frontal hemodynamics, heart rate, objective and subjective vigilance, and self-evaluation of subjective symptoms were also assessed. The fNIRS results showed a slight influence of the GSM signal on frontal cortex, with a linear increase in [HHb] as a function of time in the Real exposure condition (F(4,40)=2.67; P=0.04). No other measure showed any GSM exposure-dependent changes. These results suggest that fNIRS is a convenient tool for safely and noninvasively investigating the cortical activation in MP exposure experimental settings. Given the short-term effects observed in this study, the results should be confirmed on a larger sample size and using a multichannel instrument that allows the investigation of a wider portion of the frontal cortex.